Bullous Pemphigoid

Who gets bullous pemphigoid?

Bullous pemphigoid (BP) is rare - about 7 people in a million develop it each year. Most affected people are aged over 60. It is very rare in children. Men and women are equally affected. BP is not infectious and you cannot 'catch' it from an affected person.

What causes bullous pemphigoid?

BP is an auto-immune disease. The immune system normally makes antibodies to attack bacteria, viruses, and other 'germs'. In people with auto-immune diseases, the immune system also makes antibodies against part(s) of the body.

In people with BP, antibodies are made against the membrane between the top layer of skin (the epidermis) and the next layer (the dermis). Chemical reactions and inflammation in the skin due to this antibody attack causes fluid to build up as blisters between these two layers of skin.

It is not known why BP or other auto-immune diseases occur. It is thought that something triggers the immune system to attack the body's own tissues. Possible triggers include viruses, infection, sunlight, or other factors. A medicine is thought to be the trigger in a small number of people. For example, BP is a rare side-effect of the medicines: furosemide, sulphasalazine, penicillins, and captopril. However, no trigger is identified in most cases.

People with BP have a slightly higher than average chance of developing other auto-immune diseases such as pernicious anaemia, rheumatoid arthritis, and vitiligo.

What are the symptoms of bullous pemphigoid?

Small patches of itchy skin are typical at first. Blisters develop a week or more later. The blisters are quite firm and dome-shaped. They can range from less than 1 cm to 7 cm across. The blister fluid is usually clear, but may be blood-stained. Any area of skin can be affected but the arms, legs, armpits, and groin are the most common sites. The body may be covered in blisters but sometimes the blisters occur just in one area - often on the lower leg. The inside of the mouth is rarely affected.

The skin over the blisters is quite strong and may remain for several days before the blister bursts. A raw patch of skin is left when a blister bursts which quickly heals. Some blisters may not burst but the fluid is absorbed back into the body and the roof of the blister settles back down on the skin.

How does bullous pemphigoid progress?

BP commonly lasts 1-2 years and then often eases or goes. Future recurrences may occur, but these tend to be milder. If untreated, the blisters and raw areas of skin can cause much discomfort. There is a danger of serious infection occurring on raw areas of skin.

The diagnosis may not be clear at first. There are other causes of blisters. Therefore a small sample (biopsy) of skin may be taken. This can be looked at under the microscope and tested to confirm that the blisters are due to BP.

What is the treatment of bullous pemphigoid?

Treatment stops, or greatly reduces, the number of blisters that form.

• Steroid tablets are the usual treatment. Steroids reduce inflammation and suppress the immune system. A high dose is usually needed at first. The dose is reduced once new blisters have stopped forming. A lower daily dose is usually then needed to prevent blisters forming. The aim is to find the lowest dose needed to control symptoms. The dose needed varies from person to person. You may need steroid tablets until the disease goes (often for 1-2 years). In some cases, the dose of steroid needed to control the disease is quite high and may cause side-effects. (A separate leaflet discusses steroid tablets in more detail.)
• An immunosuppressant such as azothiaprine, cyclosporin or cyclophosphamide may also be advised in addition to steroids. The two treatments tend to work better than either alone. Also, the dose of steroid needed may be less. This means that any side-effects from steroids may be less severe.
• Steroid cream is sometimes used if the blisters are confined to a small area of skin.
• Antiseptic creams may be advised if there are large areas of raw skin. This is to reduce the chance of infection.

What is the outlook (prognosis)?

The outlook is generally good as the disease is likely to go after 1-2 years. Treatment usually keeps blisters away and is often stopped after about 2 years as it is often no longer needed. However, BP can sometimes cause serious illness which may cause death. This is because:

• Serious infection of raw skin is a danger. BP most commonly affects elderly people who are more prone to develop serious illness if a skin infection occurs.
• Side-effects from steroids and immunosuppressant medication may be a problem. One risk is that they make you more prone to serious infection.

In summary

• Bullous pemphigoid (BP) is a rare blistering disease that usually lasts 1-2 years.
• Treatments with steroids and other immunosuppressants usually control BP until it goes.
• Treatment aims to balance good control of the disease with the risks and side-effects of medication. The lowest dose that keeps the blisters away is aimed for.
• You may find the disease difficult to cope with, even when symptoms are controlled, as the treatments may cause side-effects.

Further information and support

Bullous Pemphigoid Support Group, 17 Barley Mount, Redhills, Exeter, EX4 1RP

© EMIS and PIP 2004   Updated: July 2004   Review Date: August 2005   CHIQ Accredited